Frank r



(No Model.)

k F. R. COLVIN.

TELEPHONY.

UNITED STAT S PATENT OFFI E.

FRANK R. ooLvm, on NEW YORK, N. Y.

T'ELEP\H0.NY.

SPECIFICATION forming part of Letters Patent N 0. 528,592, dated November 6, 1894. Application filed July 26,1894. Serial No. 518,611- (No model.)

To a whom it may concern: I

Beit known that I, FRANK R. COLVIN, a citizen of the United States, residing in the city, county, and State of New York, have invented certain. new and useful Improvements in Telephony, of which the following is a specification. p

This invention relates to a system of telephonic inter-communication and has for its object the placing of a plurality of subscribers instruments in multiple-arc relation to a connecting line so as to permit any subscriber of a system to communicate with any other subscriber with a minimum self-inductive interference and an economical expenditure of battery power. It involves a calling and a talking branch at each subscribers station and means for imposing upon the line at the will of the subscriber a high potential current or a low potential current so as to differentiate between the calling and talking instruments. It is especially applicable to lines in which direct battery currents are used for speech transmission, the arrangement being such that although all stations of the system except the ones talking have the call-receiving apparatus in circuit, the battery currents thrown upon line by the conversation will not actuate the call-receiving apparatus.

The invention involves the multiple-a rc system in which the several stations are provided with means for, imposing upon line a high potential signaling current ora lowpotential talking current.

It also involves a battery arrangement by which the batteries of the several subscribe rs will co-operate so as to produce upon the talking circuit a potential suitable for its length irrespective of the distance between the two stations which may be in use.

It involves also other features.

In carrying outthe invention I preferably provide at each station high potential calling and call-receiving apparatus normally in closed relation to the line, by which any subscriber of the system may be called up by a;

number of impulses corresponding to his number and a talking branch containing a battery, a carbon direct-current transmitter and a suitable receiver by which conversation may be held between two communicating subscribers.

The several features of novelty of the invention will be more particularly hereinafter described, and will be definitely indicated in the claims appended to this specification.

In the accompanying drawing which illustrates my invention is shown diagrammatically a system involving its several features.

A, B represent a line extending the length of the circuit provided at the several stations, 1, 2,3, 4, 5, 6, '7 with multiple-arc branches leading to ground ora common return and including, respectively the signaling and talking outfits of the several subscribers. At each station is provided a supporting hook 8 mounted to rock into engagement with either of two contacts 9, 10, one of which, as 10, connects with a call-sending and receiving outfit, and the other of which, 9, connects with a telephone receiver 11, a carbon transmitter 12 and battery 13. The preferred form of callsending apparatus is a magneto-generator l4.

wound to impose upon line when the crank is operated, a series of high potential impulses. By high potential I mean high relatively to the potential of the battery currents employed in the system. In the calling branch is placed a bell 15 adapted to respond to magneto impulses. The calling branch is connected to the return circuit at a point beyond the battery as indicated in the drawing. The supporting hook Sis so arranged that when in its normal position it will support the telephone 11, but when shifted to the talking contact 9, the hook will incline in a downward direction so asto shed or drop the telephone and prevent the same being supported upon I the hook unlessthe latter is restored'to its normal position, as described and claimed in a patent granted to me, No. 517,263, dated March 27, 1894. It is obviously desirable that the strength of the talking current should be substantially uniform in all conditions of service; that is to say, whether the subscribers whose instruments are located at the extreme ends of the line, or those who are adjacent to each other, are in communication. Obviously, if batteries of uniform strength were employed at the several stations the strength of the current would be muchlower when the extreme operators converse, than, for example,'when the two nearest operators converse. I therefore provide at the several subscribers stations independent batteries so arranged that the strength of current will vary according to the distance between the two subscribers who are in communication.

In the system illustrated in the drawing I have shown seven stations conected in multiple-arc relation to the same line, the batteries varying in the number of elements or electromotive-force, either as shown at stations 1, 2, 3, byhaving similar poles connected to the line, or, as shown at stations 3 and 5, by having opposite poles presented to the line soas to couple them in series and thus vary the electro-motive-force proportionately to the distance between the stations. An economical arrangement is that illustrated in the drawing, wherein say three of the stations, 1, 2 and 3, have batteries of six, four and two cells, respectively, with zinc poles to line, and stations 5, 6 and 7 have two, four and six cells, respectively, with copper poles to line, station 4 being provided with no battery. In this organization it results that if stations 1 and 2 are in communication, batteries 12 and 12 will furnish a difierential electro-motive-force of two cells which will be sufficient to deliver a proper working current over the short line connecting them; but if stations 1 and 3 are in communication, a differential current of four working cells will be delivered to the line of increased length. It stations 1 and 4; are in communication, 4 having no battery, the full energy of all the cells at station 1 will be active, delivering an electro-motive-force suitable to the distance between the stations. On the other hand, if station 5 is in communication with station 1, its two cells having the opposite pole to line, will add to the electro-motive-force of the battery at station 1 and produce a current strength sufficient for the distance between stations 1 and 5. So, if stations 1and7 are in communication, the two batteries of six cells each will be connected in series and deliver a proper working current.

The calling apparatus at the several stations involving the use of high potential induced currents may be similar throughout the system and of a character to operate the calling apparatus between the extreme stations of the system. The call-sending and receiving apparatus will preferably be provided with a high resistance ohmic or inductive so as to prevent a damaging leak of the talking currents over the several branches which are not in talking relation to line.

It will thus be seen that I provide a system in which the resistance of the talking circuit is comparatively low and noinductive apparatus except that of the two conversing subscribers will interfere with a successful transmission of speech.

I do not confine myself rigidly to the organization illustrated, as changesmay be made in the arrangement of the apparatus without departing from the scope of my claims.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. A system of telephonic intercommunication, comprising a plurality of stations connected in multiple-arc relation to the line, each station being provided with a high potential calling generator and a talking outfit organized to impose on line low potential talking currents.

2. A system of telephonic intercom munication, comprising a plurality of stations cons.

nected in multiple-arc relation to the line, each station being provided with high potential and high resistance call-receiving and transmitting apparatus and talking apparatus adapted to impose on line low potential currents arranged in independent branches of the circuit.

3. A system of telephonic intercommunication, comprising a plurality of stations connected in multiple-arc relation to a common line having high potential and high resistance calling apparatus normally in closed' relation thereto and low potential direct-current talking apparatus in normally open relation thereto.

4. A system of telephonic intercommunication, comprising a plurality of stations connected in multiple arc relation to a common line, a battery or other source of continuous current, in each station branch of the circuit the electro-motive-force of the several batteries being arranged to cooperate so that whatever the distance between two subscribers in talking relation to the line, current of substantially the same strength will be furnished.

5. A system of telephonic intercomrnunication, comprising a plurality of stations connected to a common line, call-transmitting and receiving apparatus in normally closed relation at the several stations, a normally open talking branch including a carbon transmitter and a battery, the batteries at the several stations being arranged so as to progress ively increase in electro-motive-force as the distance between the communicating subscribers is increased.

6. A system of telephonic intercommunication, comprising a plurality of stations con nected in multiple-arc relation to a common line, transmitting apparatus in each station branch of the circuit, said transmitting apparatus being of progressively increasing power as the distance between the stations increases so as to preserve a uniform strength of talking current for all communicating subscribers.

7. A system of telephonic intercommunication, comprisinga plurality of stations connected in multiple-arc relation to a common In testimony whereof I have hereunto subline, and provided with transmitters in the scribed my name this 23d day of July, A. D. several station branches whose batteries are 1894.

arranged to act conj unctively or diiferentially FRANK R. OOLVIN. todeliver an electro-motive-force proportion- Witnesses: ate to the distance between the communicat- FREDERICK A. ISHAM,

ing stations. I LAURA E. ISHAM. 

